October 19, 2011 - NASA and Japan released a
significantly improved version of the most complete
digital topographic map of Earth on Monday, produced
with detailed measurements from NASA's Terra spacecraft.

The map, known as a global digital elevation model, was
created from images collected by the Japanese Advanced
Spaceborne Thermal Emission and Reflection Radiometer,
or ASTER, instrument aboard Terra. So-called stereo-pair
images are produced by merging two slightly offset
two-dimensional images to create the three-dimensional
effect of depth.

The first
version of the map was released by NASA and Japan's Ministry of
Economy, Trade and Industry (METI) in June 2009. "The ASTER
global digital elevation model was already the most complete,
consistent global topographic map in the world," said Woody
Turner, ASTER program scientist at NASA Headquarters in
Washington. "With these enhancements, its resolution is in many
respects comparable to the U.S. data from NASA's Shuttle Radar
Topography Mission (SRTM), while covering more of the globe."

The
improved version of the map adds 260,000 additional stereo-pair
images to improve coverage. It features improved spatial
resolution, increased horizontal and vertical accuracy, more
realistic coverage over water bodies and the ability to identify
lakes as small as 0.6 miles (1 kilometer) in diameter.

"This
updated version of the ASTER global digital elevation model
provides civilian users with the highest-resolution global
topography data available," said Mike Abrams, ASTER science team
leader at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"These data can be used for a broad range of applications, from
planning highways and protecting lands with cultural or
environmental significance, to searching for natural resources."

The ASTER
data cover 99 percent of Earth's landmass and span from 83
degrees north latitude to 83 degrees south. Each elevation
measurement point in the data is 98 feet (30 meters) apart.

NASA and
METI are jointly contributing the data for the ASTER topographic
map to the Group on Earth Observations, an international
partnership headquartered at the World Meteorological
Organization in Geneva, Switzerland, for use in its Global Earth
Observation System of Systems. This "system of systems" is a
collaborative, international effort to share and integrate Earth
observation data from many different instruments and systems to
help monitor and forecast global environmental changes.

ASTER is one of
five instruments launched on Terra in 1999. ASTER acquires images from
visible to thermal infrared wavelengths, with spatial resolutions
ranging from about 50 to 300 feet (15 to 90 meters). A joint science
team from the United States and Japan validates and calibrates the
instrument and data products. The U.S. science team is located at JPL.

NASA, METI, Japan's Earth Remote Sensing Data Analysis
Center (ERSDAC), and the U.S. Geological Survey
validated the data, with support from the U.S. National
Geospatial-Intelligence Agency and other collaborators.
The data are distributed by NASA's Land Processes
Distributed Active Archive Center at the U.S. Geological
Survey's Earth Resources Observation and Science Center
in Sioux Falls, S.D., and by ERSDAC in Tokyo.